scow bow trimaran

Discussion in 'Multihulls' started by dsigned, Apr 27, 2018.

  1. dsigned
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    dsigned O.R.C. Hunter

    I've been looking at trailer sailer trimarans recently, and was thinking that they look great except that they really have almost no space. So I was thinking it might be interesting to do a scow bow trimaran to maximize interior space, while keeping overall length within trailerable limits. I read (skimming, except for the last couple pages, which I actually read) this thread:
    Round full blunt bow on a cruising catamaran https://www.boatdesign.net/threads/round-full-blunt-bow-on-a-cruising-catamaran.57120/page-4

    Seems like you could get away with a relatively "blunt" bow (e.g. something looking more like the nose of an airliner) to get enough interior volume to manage something seaworthy that you wouldn't mind spending a few weeks living on as opposed to something that is pretty much only good for an afternoon (or maybe one night).

    The impetus is that I've been looking at stuff to putter around the Bahamas. I like multihulls for the stability under way (not as much heel for the missus and kiddos) and at rest, but also for the shallow draft.

    Problem is, there really aren't any multihulls that work for this. The corsairs, etc. aren't really suited for extended trips with anyone who isn't thinking of it as camping. Some of the older tris seem to have a bit more cabin, but apparently have a reputation for not being terribly seaworthy (though I'm not sure how much better the corsairs etc fare in this regard).
     
  2. waynemarlow
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    waynemarlow Senior Member

    Mmmm I think you are looking for a bit of the holy grail of sailing, good accommodation with a 20 - 22 ft boat that's easy to trailer about.

    Having spent a long time designing such a Tri, it is neigh on impossible, as its not the width but the length that always forces a compromise. My 20 fter almost gets there with its fat belly design but still doesn't quite get that nice double cabin in the front that you need. Nearly but not quite, its more of 1 3/4 berth.

    What I have come to accept is that you can build a 20 ft over nighter with tight room for two in the cabin and a generous boom tent for two over the rear, with the ability to have almost nothing as its draft, which lets you into bays and habours most boats don't dare. Once close to land you then have all the choices of tents and local accommodations without the up keep costs of a larger boat. Also bare in mind most land lubber wives and family can endure 1 or 2 nights out in the wilds but give them the opportunity of a nice bed, shower, internet and other equally reticent company in a bar having sailed from point A to point B in a rapid 4 - 5 hours max, then your cramped 20fter becomes simply a problem of retaining their company.
     
  3. dsigned
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    dsigned O.R.C. Hunter

    In the US the max trailer length is about 28 ft on most states, so you can get 24-27ft. Still pretty limited, but maybe enough?
     
  4. waynemarlow
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    waynemarlow Senior Member

    The F28's are a big boat and would offer all you need, but they are a big boat to handle with a young family particularly getting on and of the water + trailing.
     
  5. dsigned
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    dsigned O.R.C. Hunter

    Yeah, think F-27 except with a center hull shaped more like this:

    [​IMG]

    Again, the idea being to get as much interior volume for a given length as possible.
     

    Attached Files:

  6. waynemarlow
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    waynemarlow Senior Member

    Bit like this then,

    2015-09-17 09.48.17.jpg
     
  7. dsigned
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    dsigned O.R.C. Hunter

  8. upchurchmr
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    upchurchmr Senior Member

    When you bloat the main hull it destroys some of the reasons for a trimaran.
    Have you looked at a Horstman? Older, it defined the term roomeran.
     
  9. dsigned
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    dsigned O.R.C. Hunter

    I think "destroys" is too strong a term. There's certainly a diminishing returns thing happening. But where and how this transition happens seems poorly understood to me. That the scow-bow has been as successful in the mini-transat as it has been in the comparatively well documented land of monohulls suggests to me that it's understood even less in the comparatively poorly understood domain of multis. In any case, your return on investment for weight in building amas versus ballast

    As for the Horstman, my understanding was that they were not particularly good in rougher seas (that is, not terribly seaworthy). Also, I'm not suggesting a particularly heavy tri, just one that you can lay down in.
     
  10. upchurchmr
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    upchurchmr Senior Member

    Well I think you just named one reason not to bloat.

    What's wrong with a F-24? I think you can lay down in those. One on each side. Well known.
    Even going back a long way, what about a Buccaneer 24. Two bunks in those.
    Neither are bloated.

    Why are you comparing a hard core, designed for a specific course, racing boat driven by really hard core sailors to a boat to "putter around on"?
     
  11. Steve W
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    Steve W Senior Member

    Where are you getting this idea that older tris are not seaworthy? Quite the opposite is true. Many Horstmans, Pivers, Browns, Cross etc have done long passages, circumnavigations etc.A 35ft Horstman circumnavigated including cape horn many years ago so pretty seaworthy I think. Much better cruising boats than almost any modern tris which almost without exception are designed for performance rather than cruising. Of course not in the size you are talking about but Horstman has a very nice 24ft Tri star which can be built to fold and has a couple of double wing berths which may suit you. Bernard Rhodes has a neat little 22ft tri design which is a development of the little tri he sail from England to New Zealand nearly 50 years ago, more demountable than folding though.
     
  12. cavalier mk2
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    cavalier mk2 Senior Member

    Why not just make a scow? In that size range it will win on space and load and maybe speed if you have much of a load.
     
  13. dsigned
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    dsigned O.R.C. Hunter

    [​IMG]

    Sketch of "scow". It's really not that different than a normal tri, just a little fuller for a little longer near the nose. The scale is roughly 6:1 L:W for the main hull for about 4.5 feet wide at the waterline and a length of about 27 feet. The flare represents the maximum width, likely right around where the ama braces meet the hull. I'd expect you'd lose a little speed on the top end, but I would be very surprised if it was much, except maybe in light wind. Might also lose a little bit of pointing ability. But again, as a trade off for a tri with overnight accommodations that are better than non-existent, I think it might be worth the trade.
     
  14. Dolfiman
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    Dolfiman Senior Member

    I bet that can work very well, as the main hull fate is to be flush with the water surface,it is in coherence with a scow bow. Another potential advantage, a lot less spray from this bow. Upwind, the slamming issue should be less important than for a beamy monohull sailing nose-down with a scow bow.
     

  15. Dolfiman
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    Dolfiman Senior Member

    … and I did a rapid illustration with Gene-Hull of a tri main hull without and with scow bow, here attached.
     

    Attached Files:

    dsigned and Doug Lord like this.
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